1 files changed, 42 insertions, 0 deletions
diff --git a/actionpack/lib/action_controller/middleware_stack.rb b/actionpack/lib/action_controller/middleware_stack.rb
new file mode 100644
index 0000000000..1864bed23a
--- /dev/null
+++ b/actionpack/lib/action_controller/middleware_stack.rb
@@ -0,0 +1,42 @@
+module ActionController
+  class MiddlewareStack < Array
+    class Middleware
+      attr_reader :klass, :args, :block
+
+      def initialize(klass, *args, &block)
+        @klass = klass.is_a?(Class) ? klass : klass.to_s.constantize
+        @args = args
+        @block = block
+      end
+
+      def ==(middleware)
+        case middleware
+        when Middleware
+          klass == middleware.klass
+        when Class
+          klass == middleware
+        else
+          klass == middleware.to_s.constantize
+        end
+      end
+
+      def inspect
+        str = @klass.to_s
+        @args.each { |arg| str += ", #{arg.inspect}" }
+        str
+      end
+
+      def build(app)
+        klass.new(app, *args, &block)
+      end
+    end
+
+    def use(*args, &block)
+      push(Middleware.new(*args, &block))
+    end
+
+    def build(app)
+      reverse.inject(app) { |a, e| e.build(a) }
+    end
+  end
+end